do yourself a favour and by her a liquid medicine dropper from the drug store. It's very easy to use and accurate as well.
Start her off around 25mcgs and work her way up to 80mcgs' and definitely not more han 100mcgs. To measure 25mcgs, you'll probably need to use a slin pin to measure it, ans the dropper doesn't meeasure that small.
Oh, and I like to administer the doses 2x a day, so @ 80mcgs she'll do 40 in the morning and 40 around 3-4pm (at 25mcgs she can just do it once a day). I do'nt recommend taking it later than 4 because it will keep you up at night, at least it does to me and many others.